Search Results (378)

This paper analyzes a surface plasmon resonance (SPR) sensor utilizing silver (Ag) and Zirconium Nitride (ZrN) for glucose concentration detection in urine samples by the transfer matrix method (TMM). For effective SP excitation, a high-RI BAF10 prism is thought to be used as the coupling layer in the suggested theoretical design. The performance of the proposed SPR biosensor is theoretically evaluated using the wavelength interrogation technique by analyzing wavelength sensitivity (WS), detection accuracy (DA), figure of merit (FoM), and penetration depth (PD) parameters. Glucose in urine samples serves as the sensing medium (SM) in this biosensor configuration. The sensor achieves a maximum wavelength sensitivity of 6416.66 nm/RIU with a penetration depth of 297.53 nm. The ZrN structure incorporated in the biosensor demonstrates enhanced wavelength sensitivity through its molecular recognition sites that provide strong binding with glucose molecules. The improved wavelength sensitivity is attributed to the greater resonance wavelength shift produced by ZrN, resulting in significant performance enhancement of the biosensor for glucose detection. Benefits of the proposed SPR biosensor include very small urine sample concentration requirements (usually 0 mg/dL to 10 g/dL), compatibility with compact prism-based configurations that support the development of portable and affordable point-of-care devices, and quick detection within a few seconds due to real-time plasmonic response. These features make the sensor ideal for rapid, minimally invasive, and field-deployable glucose monitoring in both home and clinical relevance. Full article

Strawberry (Fragaria × ananassa (Weston) Rozier) is a high-value crop whose market success depends on fruit quality traits such as sweetness, firmness, and pigmentation. In sustainable agriculture, wood distillates are gaining interest as natural biostimulants. This study evaluated the effects of foliar application of two commercial wood distillates (WD1 and WD2) and one produced in a pilot plant at the Institute for Bioeconomy of the National Research Council of Italy (IBE-CNR) on strawberry physiology, fruit yield, and fruit quality under greenhouse conditions. Non-destructive ecophysiological measurements were integrated using optical sensors for proximal phenotyping, enabling continuous monitoring of plant physiology and fruit ripening. Leaf gas exchange and chlorophyll fluorescence were measured with a portable photosynthesis system, while vegetation indices and pigment-related parameters were obtained using spectroradiometric sensors and fluorescence devices. To assess the functional relevance of vegetation indices, a linear regression analysis was performed between net photosynthetic rate (A) and the Photochemical Reflectance Index (PRI), confirming a significant positive correlation and supporting PRI as a proxy for photosynthetic efficiency. All treatments improved photosynthetic efficiency during fruiting, with significant increases in net photosynthetic rate, quantum yield of photosystem II, and electron transport rate compared to control plants. IBE-CNR and WD2 enhanced fruit yield, while all treatments increased fruit soluble solids content. Non-invasive monitoring enabled real-time assessment of physiological responses and pigment accumulation, confirming the potential of wood distillates as biostimulants and the value of advanced sensing technologies for sustainable, data-driven crop management. Full article

The growing demand for advanced health-monitoring technologies has intensified the need for early diagnosis of incurable diseases and timely detection of life-threatening conditions. Among various detection modalities, electrochemical sensing has emerged as a particularly promising approach due to its simplicity, cost-effectiveness, high sensitivity, rapid response, ease of miniaturization, and compatibility with portable, wearable, and implantable platforms. The performance of electrochemical sensors is strongly governed by the morphology and physicochemical properties of electrode materials. In this context, MXenes, 2D transition-metal carbides, nitrides, and carbonitrides have attracted increasing attention for sensing applications owing to their high electrical conductivity, large surface area, hydrophilicity, and rich surface chemistry. However, their practical implementation is hindered by oxidation and environmental instability, while surface modification strategies, although improving stability, may compromise intrinsic electrochemical activity and biocompatibility. Notably, MXene-based hybrids consistently demonstrate enhanced sensing performance, underscoring their potential for flexible and wearable electrochemical devices. Despite rapid progress in this field, a comprehensive review addressing the significance of MXene hybrids, their structure–property–performance relationships, and their role in electrochemical detection remains limited. Therefore, this review summarizes recent advances in MXene-based hybrid materials for electrochemical sensing and biosensing of biologically relevant analytes, with an emphasis on design strategies, functional enhancements, and their prospects for next-generation health-monitoring technologies. Full article

This review presents a critical and comparative analysis of carbon-based electrochemical sensing platforms for the determination of heavy metal ions in water, with emphasis on Pb²⁺, Cd²⁺, and Hg²⁺. The growing discharge of industrial and mining effluents has led to persistent contamination of aquatic environments by toxic metals, creating an urgent need for sensitive, rapid, and field-deployable analytical technologies. Carbon-based nanomaterials, including graphene, carbon nanotubes (CNTs), and MXene, have emerged as key functional components in modern electrochemical sensors due to their high electrical conductivity, large surface area, and tunable surface chemistry. Based on reported studies, typical detection limits for Pb²⁺ and Cd²⁺ using differential pulse voltammetry (DPV) on glassy carbon and thin-film electrodes are in the range of 0.4–1.2 µg/L. For integrated thin-film sensing systems, limits of detection of 0.8–1.2 µg/L are commonly achieved. MXene-based platforms further enhance sensitivity and enable Hg²⁺ detection with linear response ranges typically between 1 and 5 µg/L, accompanied by clear electrochemical or optical signals. Beyond conventional electrochemical detection, this review specifically highlights self-sustaining visual sensors based on MXene integrated with enzyme-driven bioelectrochemical systems, such as glucose oxidase (GOD) and Prussian blue (PB) assembled on ITO substrates. These systems convert chemical energy into measurable colorimetric signals without external power sources, enabling direct visual identification of Hg²⁺ ions. Under optimized conditions (e.g., 5 mg/mL GOD and 5 mM glucose), stable and distinguishable color responses are achieved for rapid on-site monitoring. Overall, this review not only summarizes current performance benchmarks of carbon-based sensors but also identifies key challenges, including long-term stability, selectivity under multi-ion interference, and large-scale device integration, while outlining future directions toward portable multisensor water-quality monitoring systems. Full article

Accurate potentiometric sensing critically depends on the stability and reproducibility of the reference electrode potential. Conventional liquid-filled Ag/AgCl or calomel electrodes, though well-established, are poorly compatible with miniaturized, portable, or long-term in situ sensing devices due to electrolyte leakage, junction potential instability, and maintenance requirements. Recent advances in solid-state and membrane-based reference electrodes offer a promising alternative by eliminating the liquid junction while maintaining stable and well-defined potential. This review summarizes the advancements in polymer-based and composite reference membranes, focusing on material strategies, stabilization mechanisms, and integration approaches. Emphasis is placed on ionic-liquid-doped membranes, conducting polymers, lipophilic salts, and carbon nanomaterials as functional components enhancing interfacial stability and charge transfer. The performances of various architectures, solid-contact, liquid-junction-free, and quasi-reference systems, are compared in terms of potential drift, matrix resistance, biocompatibility, and manufacturability. Furthermore, recent developments in printed, microfluidic, and wearable potentiometric platforms demonstrate how reference membrane innovations enable reliable operation in compact, low-cost, and flexible analytical systems. The review outlines current trends, challenges, and future directions toward universal, miniaturized, and leak-free reference electrodes suitable for innovative sensing technologies. Full article

The accurate monitoring of metal ions is essential for applications that include environmental protection, food safety, and biomedical diagnostics. These areas depend on highly sensitive and selective methods for detecting both toxic and biologically relevant ions. Electrochemical sensors have emerged as promising devices due to their excellent sensitivity, cost-effectiveness, and ease of use. Within these sensor systems, ionophores, either synthetic or natural ligands that exhibit selective ion binding, are fundamental in boosting analytical performance. This review outlines the current progress of ionophore-based electrochemical sensors for metal-ion analysis, emphasizing material selection, architectural strategies, and practical applications. Key classes of ionophores, such as crown ethers, calixarenes, Schiff bases, porphyrins, and oxime derivatives, are discussed with an emphasis on their recognition mechanisms. We also examine strategies for incorporating ionophores into diverse electrochemical sensor configurations and explore recent advances in technologies, such as all-solid-state sensor construction and the development of portable analytical devices. This review bridges the chemistry of ionophores with sensor engineering and serves as a resource for the rational development of advanced platforms for metal-ion sensing. Full article

Miniaturized long-wavelength infrared (LWIR) imaging systems are highly desirable for applications such as portable thermal sensing, unmanned surveillance, and medical diagnostics. Conventional refractive optics in the LWIR regime often require multiple lens configurations to extend depth of field (DoF), leading to increased size, weight, and cost. Although existing LWIR metalenses demonstrate competent capabilities, comprehensive approaches to DoF engineering have yet to be explored. Here, we demonstrate a miniature large-DoF camera using a metalens. The designed metalens features a 14 mm diameter aperture and weighs only 0.8 g while maintaining sharp focus over a working distance ranging from 1 m to 22 m. By leveraging subwavelength phase engineering, the metalens achieves high-resolution imaging with low aberration. The integrated camera exhibits an ultra-compact form factor, i.e., 2.3 cm × 2.3 cm × 1.2 cm (length × width × height) and weighs just 25 g. Experimental results confirm the superior DoF performance, enabling clear imaging across varying distances without mechanical refocusing. The advance provides a promising pathway toward ultra-compact, large-DoF LWIR imaging systems for applications ranging from autonomous vehicles to portable medical diagnostics and miniature surveillance devices. Full article

Capillary-driven microfluidic chips have emerged as promising platforms for point-of-care diagnostics, offering portable, inexpensive, and pump-free operation. Accurate tracking of cell flow in these systems is vital for quantitative applications such as on-chip cytometry, cell counting, and biomechanical analysis. However, tracking in capillary-driven devices is challenging due to rapid cell displacements, flow instabilities, and visually similar cells. Under these conditions, conventional tracking algorithms such as TrackPy, TrackMate, SORT, and DeepSORT exhibit frequent identity switches and trajectory fragmentation. Here, we introduce FloCyT, a robust, high-speed centroid tracking tool specifically designed for capillary-driven and microfluidic flow. FloCyT leverages microchannel geometry for tracking and uses anisotropic gating for association, global flow-aware track initialisation, and channel-specific association. This enables precise tracking even under challenging conditions of capillary-driven flow. FloCyT was evaluated on 12 simulated and 4 real patient datasets using standard multi-object tracking metrics, including IDF1 and MOTA, ID switches, and the percentage of mostly tracked objects. The results demonstrate that FloCyT outperforms both standard and flow-aware-modified versions of TrackPy and SORT, achieving higher accuracy, more complete trajectories, and fewer identity switches. By enabling accurate and automated cell tracking in capillary-driven microfluidic devices, FloCyT enhances the quantitative sensing capability of image-based microfluidic diagnostics, supporting novel, low-cost, and portable cytometry applications. Full article

The demand for low-cost, portable, and sensitive analytical devices has fueled the development of 3D-printed biosensors. This study evaluates the effect of silk fibroin incorporation on the electrical properties of graphite-PLA electrodes manufactured via 3D printing. Electrochemical Impedance Spectroscopy (EIS) method was utilized to assess capacitive–resistive behavior under dry conditions, and with PBS buffer, at fibroin concentrations of 0%, 0.04%, 0.4%, and 4%. Fibroin modulated impedance magnitude values without a clear trend, indicating the presence of additional influencing factors. The results promote better understanding of biofunctionalization effects in 3D-printed electrodes and support their potential for biomedical, environmental, and industrial sensing applications. Full article

Environmental conditions like temperature, humidity, light, and gas levels directly affect human health, agriculture, and industrial processes. Monitoring these factors in real time is necessary for detecting dangerous situations early and making informed choices. This work presents a compact, mobile, IoT-enabled device that measures environmental data and sends it wirelessly for remote access. The system uses the ESP32 microcontroller, chosen for its low power use, built-in Wi-Fi, and ease of connecting with sensors and cloud services. Key sensors include the DHT22 for temperature and humidity, MQ135 for ammonia and gas detection, and an LDR for checking light intensity. An infrared (IR) sensor identifies obstacles, and a buzzer alerts users to dangerous conditions. The collected data appears on a 16X2 LCD for local monitoring. It is also transmitted to the ThingSpeak cloud platform for long-term storage and visualization. Users can view this data in real time through the Blynk mobile application, which also enables remote control of the device. The system is built for mobility. It operates with DC motors powered by an L298N motor driver. This lets it navigate different environments and collect data from various locations. This feature gives more flexibility and improves the system’s effectiveness compared to traditional stationary monitoring units. The innovative part of this project is the mix of real-time sensing, autonomous movement, and cloud connectivity in a low-cost, portable setup. The system was tested in controlled environments and consistently provided reliable readings. Its practical uses include smart agriculture, urban air quality monitoring, and industrial safety. Full article

In the last few decades, several wearable devices have been designed to monitor respiration rate to capture pulmonary signals with a higher accuracy and reduce patients’ discomfort during use. In this article, we present the design and implementation of a device for the real-time monitoring of respiratory system movements. When breathing, the circumference of the abdomen and thorax changes; therefore, we used a Force-Sensing Resistor (FSR) attached to a Printed Circuit Board (PCB) to measure this variation as the patient inhales and exhales. The mechanical strain this causes changes the FSR electrical resistance accordingly. Also, for streaming this variable resistance on an Internet of Things (IoT) platform, Bluetooth Low Energy (BLE) 5 is utilized due to its adequate throughput, high accessibility, and the possibility of power consumption reduction. In addition to the sensing mechanism, the device includes a compact, energy-efficient micro-controller and a three-axis accelerometer that captures body movement. Power is supplied by a rechargeable Lithium-ion Polymer (LiPo) battery, and energy usage is optimized using a buck converter. For comfort and usability, the enclosure was 3D printed using Stereolithography (SLA) technology to ensure a smooth, ergonomic shape. This setup allows the device to operate reliably over long periods without disturbing the user. Altogether, the design supports continuous respiratory tracking in both clinical and home settings, offering a practical, low-power, and portable solution. Full article

In automated laboratories, ambient monitoring and precise object tracking are essential for safety and system reliability. In this paper, we present the development and evaluation of a low-cost, portable sensor node for environmental sensing and ultrawideband (UWB) based localization. The sensor node integrates a set of commercial gas sensors for measuring environmental parameters and an ultra-wideband unit for object tracking. The device has an IoT microcontroller that can efficiently process the data from both environmental sensors and the location information from the UWB module and transmit it wirelessly to the cloud/monitoring server via Wi-Fi user datagram protocol (UDP). A custom Python application was developed for real-time monitoring, implementing trilateration and least-squares algorithms for accurate indoor positioning. Experimental results showed a location accuracy better than 50 cm under line-of-sight conditions. Full article

Background: Inertial measurement units (IMUs) represent a relatively new and promising method for motion analysis. Their main advantages include small size and portability, combined with the use of advanced technologies. To date, few studies have investigated the application of these devices for proprioception assessment, and none have focused specifically on the elbow joint. Therefore, the aim of our study was to assess reliability and validate the protocol of elbow proprioception evaluation using inertial motion sensors. Methods: Twenty healthy participants underwent active and passive proprioception assessments based on joint position sense (JPS). Two researchers independently performed evaluation. The analyzed data was the error of reproduction of joint position (ERJP). IMU (RSQ Motion sensors) were used for angular joint position assessment and validated against Biodex System 4. Results: Inter-rater reliability for passive proprioception was good, with a Kendall’s coefficient of 0.77 (p < 0.05) for both RSQ Motion sensors and BIODEX, while active proprioception measured with RSQ Motion sensors showed slightly lower reliability (Kendall’s coefficient of 0.66, p < 0.05). Intra-rater reliability had similar results, with Kendall’s coefficients of 0.74 for passive BIODEX proprioception examination, 0.75 for passive RSQ Motion sensor testing and 0.65 for active proprioception (p < 0.05) measured with RSQ Motion sensors. The Bland–Altman plot revealed an equal distribution of results, which were within the limits of agreement (LoA). Conclusions: These results suggest proprioception assessment by JPS using inertial motion sensors is reliable and valid. It is an easy to use, light, portable, and inexpensive alternative for proprioception assessment, although further research in diverse clinical settings is needed. Full article

The detection and monitoring of ions are essential for a broad range of applications, including industrial process control and biomedical diagnostics. Traditional ion-sensitive field-effect transistors require bulky and expensive reference electrodes, which face several limitations, including device miniaturization, high fabrication costs, and incompatibility with semiconductor manufacturing processes. Here, we introduce a reference-less semiconductor ion sensor (RELESIS) that utilizes anodic aluminum oxide film as both the sensitive and dielectric layer. The RELESIS is composed of a metal-oxide-semiconductor field-effect transistor and an interdigital electrode, which fundamentally eliminates the need for a reference electrode, thereby enabling device miniaturization. During fabrication, the anodic oxidation process is employed in place of the expensive atomic layer deposition method, significantly reducing manufacturing costs while maintaining high surface quality. In practical measurements, the RELESIS device demonstrated an excellent pH sensitivity of 57.8 mV/pH with a low hysteresis of 7 mV. As a proof-of-concept application, the RELESIS device was employed for real-time, non-destructive monitoring of milk freshness, accurately detecting pH changes from fresh to spoiled in milk samples. The combination of reference-less structure, low-cost fabrication, and superior sensing performance positions this technology as a promising platform for next-generation portable ion sensing systems in food safety, environmental monitoring, and point-of-care diagnostics. Full article

Impedimetric biosensors have emerged as a versatile class of electrochemical devices, enabling highly sensitive and real-time detection of diverse analytes. Their applications extend across healthcare diagnostics, environmental monitoring, food safety, and agriculture. By virtue of their compact size, high sensitivity, selectivity, portability, and ease of operation, these sensors have advanced rapidly in both research and practical applications. This review consolidates the wide spectrum of current applications and technological advances reported in the literature. Additionally, it examines the prospects of integrating impedimetric biosensors with emerging technology fields, including artificial intelligence, machine learning, and flexible and wearable devices. By providing an overview of the different categories of impedimetric biosensors, their detection strategies, sensing modalities, and applications, this review presents a comprehensive perspective on the current progress and future opportunities in impedimetric biosensing. Full article